[RocktimusPryme]

Originally Posted by stoveboltgeek

Coming from the world of '55-57 Chevys with first-generation small blocks (265 and 283), if it's running over 190 degrees with a 180 thermostat, something's wrong. (My experience was more like 180-185, even on 90+ degree days.) And, these cars didn't even come with a fan shroud or fan clutch. So, I'm trying to understand the differences here.


So, with a 195 degree thermostat, I would expect 195-205 degrees. OTOH, if you used a 180 degree thermostat, I would expect 180-190. But, I'm gathering that often isn't the case?

(This would be one advantage to an electric fan - it won't interfere with airflow at speed.)

Unpacking a couple of things with your statement there, you may have answered your own question about what the difference is when you are talking about early SBC tri-five cars vs some pontiacs.

A V8 tri-five radiator from cold case in 374 SQin of surface area for a 265 or 283. A non AC 65 GTO radiator is 399 SQin. for a 389. So you have 7% more radiator for 27% more engine.

Now say someone yanks out the 389 and installs a hot 462 in a car behind a radiator that was probably barely enough for the 389. You can see where I am going with this. But I think the same would apply to the tri-five when someone stuffs a 540 in there. Its not brand specific. 90% of this battle is simply available radiator surface area vs powerplant its being asked to cool. I just dont think the perception that a 55 chevy cools better than a Pontiac is accurate. Because its rarely an apples to apples comparison.

On a normal, not scalding hot ambient day I would agree if you engine is running way hotter than the thermostat rating there is an issue with your cooling system. Thats no different on a pontiac than a chevy.

And electric fans can be restrictions at highway speed, but its most common with dual fan setups that just block too much of the back of the radiator to flow.

FWIW the basic cheap aluminum radiator in my 62 cools the olds 455 in it just fine with a clutch fan and no shroud. But that smogger era probably doesnt generate enough power to make any real heat.